52 PLANT PROPAGATION 



Thielavia basicola and Phoma beticola. By experimenting with soil 

 infested with Pythium debaryauum, heating to 130 to 212 degrees 

 and treating with 20 to 30 per cent solutions of formalin and various 

 quantities of carbon bisulphide, he found that Camelina, a plant 

 very susceptible to attacks of this fungus made good growths, the 

 action of this fungus being reduced even to nothing. 



79.' Damping-off seedlings in plant beds, according to the Minne- 

 sota station, is commonly caused by Pythium debaryanum or Rhizoc- 

 tonia. These attack a large variety of plants as well as live upon 

 dead organic matter in the soil. Very little can be done to check 

 the disease when such conditions prevail. Therefore methods which 

 kill fungi are needed to prevent the disease. The preventive 

 methods must be applied before sowing the seed, otherwise the seed 

 will be killed also. 



FIG. 43 WORK IN THE CUTTING BENCH 



1. Opening a furrow with a wooden label. 2. Firming the cuttings in the 

 sand, side view. 3. End view. 4. Removing rooted cuttings for potting. 



Chemical agents have been tested as fungicides against damping- 

 off, but of these formalin alone has proved of value. Treatment of 

 the soil with formalin (one part formalin to 100 of water and lesser 

 strengths), as frequently recommended, does not kill the fungus. 

 Although it may check the disease for some time it will allow damp- 

 ing-off to develop later if weather conditions permit. The value of 

 formalin at these strengths, therefore, depends largely on the time 

 weather conditions favorable to damping-off appear. 



